Method and apparatus for creating formed elements used to make wound stents
A method for forming a wave form for a stent includes moving a first forming portion of a first forming member across an axis along which a formable material is provided in a first direction substantially perpendicular to the axis to engage and deform the formable material while engaging the formable material with a first forming portion of the second forming member. The method includes moving the first forming portion of the first forming member and the first forming portion of the second forming member across the axis in a second direction that is substantially opposite the first direction to draw and form the formable material over the first forming portion of the second forming member, disengaging the first forming member from the formable material, and moving the first forming member to position a second forming portion of the first forming member to face the formable material.
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1. Field of the Invention
The present invention is generally related to an apparatus and method for forming a wave form for a stent. More particularly, the present invention is related to an apparatus and method for forming the wave form from a formable material, such as a wire or a strip of material.
2. Background of the Invention
A stent is typically a hollow, generally cylindrical device that is deployed in a body lumen from a radially contracted configuration into a radially expanded configuration, which allows it to contact and support a vessel wall. A plastically deformable stent can be implanted during an angioplasty procedure by using a balloon catheter bearing a compressed or “crimped” stent, which has been loaded onto the balloon. The stent radially expands as the balloon is inflated, forcing the stent into contact with the body lumen, thereby forming a support for the vessel wall. Deployment is effected after the stent has been introduced percutaneously, transported transluminally, and positioned at a desired location by means of the balloon catheter.
Stents may be formed from wire(s) or strip(s) of material, may be cut from a tube, or may be cut from a sheet of material and then rolled into a tube-like structure. While some stents may include a plurality of connected rings that are substantially parallel to each other and are oriented substantially perpendicular to a longitudinal axis of the stent, others may include a helical coil that is wrapped or wound around a mandrel aligned with the longitudinal axis at a non-perpendicular angle.
Stent designs that are comprised of wound materials generally have complex geometries so that the final stents may be precisely formed. The small size and complexity of some stent designs generally makes its formation difficult. Wound stents are formed such that when unsupported, they create the desired stent pattern and vessel support. This process generally involves winding a source material around a supporting structure such as a rod or mandrel and creating a helical or spring-like wrap pattern. To provide greater support, along this wrapped element, geometries are formed into the source material to better support the tissue in between each wrap, usually of sinusoidal nature. A potential down side to a wrapped stent is that the ends of the stent are generally not perpendicular to the longitudinal axis of the stent, but rather terminate at a pitch angle induced by the helical wrapping.
SUMMARY OF THE INVENTIONEmbodiments of the present invention describe an apparatus and method for forming a wave form for a stent that provides formed geometries that can alter a pitch angle such that the wound stent terminates at a substantially perpendicular angle to the longitudinal axis of the stent. More specifically, the apparatus and method according to embodiments of the present invention allow for the amplitude and wavelength of any individual or half element of the wave form to be manipulated to provide the desired interwrap support.
According to an aspect of the present invention, there is provided a method for forming a wave form for a stent. The method includes providing a length of a formable material from a supply of the formable material in a feeder along an axis in a first direction in between a first forming member and a second forming member, the second forming member being positioned closer to the feeder than the first forming member, and moving a first forming portion of the first forming member across the axis in a second direction substantially perpendicular to the first direction to engage and deform the formable material while engaging the formable material with a first forming portion of the second forming member. The method also includes moving the first forming portion of the first forming member and the first forming portion of the second forming member across the axis in a third direction that is substantially opposite the second direction to draw and form the formable material over the first forming portion of the second forming member, disengaging the first forming member from the formable material, and moving the first forming member in a fourth direction substantially perpendicular to the first direction, the second direction, and the third direction. The method also includes moving the first forming member and the second forming member relative to each other so that the first forming member is positioned closer to the feeder than the second forming member, moving a second forming portion of the first forming member into engagement with the formable material, and moving the second forming portion of the first forming member and the first forming portion of the second forming member across the axis in the second direction to draw and form the formable material over the second forming portion of the first forming member.
According to an aspect of the present invention, there is provided a forming apparatus configured to form a wave form for a stent out of a formable material. The wave form includes a plurality of substantially straight portions and a plurality of curved portions. The apparatus includes a feeder constructed and arranged to receive a supply of the formable material and to provide the formable material along a feed axis, and a first forming member configured to be movable along three orthogonal axes. The first forming member comprises a first forming portion and a second forming portion having a shape different from the first forming portion. Each of the first forming portion and the second forming portion is configured to engage and deform the formable material. The apparatus also includes a second forming member positioned on an opposite side of the feed axis relative to the first forming member. The second forming member is configured to be movable along the three orthogonal axes and comprises a first forming portion configured to engage and deform the formable material. The apparatus also includes a controller in communication with the feeder, the first forming member, and the second forming member. The controller is configured to control movement of the first and second forming members along the three orthogonal axes to form the wave form.
According to an aspect of the present invention, there is provided a method for forming a wave form for a stent. The method includes providing a length of a formable material from a supply of the formable material in a feeder along a feed axis in a first direction in between a first forming member and a second forming member, the second forming member being positioned closer to the feeder than the first forming member, moving a first forming portion of the first forming member into contact with the formable material and across the feed axis in a second direction substantially perpendicular to the first direction, and folding the formable material over a first forming portion of the second forming member by moving the second forming member and the first forming member in a third direction substantially opposite the second direction and moving the second forming member and the first forming member in a fourth direction substantially opposite the first direction. The method also includes disengaging the first forming member from the formable material, moving the first forming member in a fifth direction substantially perpendicular to the first direction, the second direction, the third direction, and the fourth direction, and moving a second forming portion of the first forming member into engagement with the formable material at a position closer to the feeder than the second forming member. The method also includes drawing a length of the formable member from the feeder with the first forming member and the second forming member, and folding the formable material over the second forming portion of the first member by moving the first forming member and the second forming member in the second direction and moving the first forming member and the second forming member in the fourth direction.
Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and use of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.
The forming apparatus 10 also includes a first forming member 20 and a second forming member 30. As illustrated in
Similar to the first forming member 20, the second forming member 30 includes a first forming portion 32 that is substantially cylindrical in shape to provide a first engaging surface 33, a second forming portion 34 that is substantially cylindrical in shape to provide a second engaging surface 35, a third forming portion 36 that is substantially cylindrical in shape to provide a third engaging surface 37, and a fourth forming portion 38 that is substantially cylindrical in shape to provide a fourth engaging surface 39. In the illustrated embodiment, the first forming portion 32 has a diameter that is greater that a diameter of the second forming portion 34, which is greater than a diameter of the third forming portion 36, which is greater than a diameter of the fourth forming portion 38. The different diameters of the forming portions 32, 34, 36, 38 provide the engaging surfaces 33, 35, 37, 39 with different radii of curvature, and are configured to engage the formable material 12 on one side thereof and deform the formable material 12 into a desired shape, as discussed in further detail below.
The first engaging member 20 and the second engaging member 30 may include more or less engaging surfaces with different radii of curvatures than illustrated. In an embodiment, each of the first engaging member 20 and the second engaging member 30 may include engaging surfaces that have radii of curvatures. For example, the radius of curvature for each engaging surface described herein may be selected from the group consisting of 0.002″, 0.003″, 0.004″, 0.005″, and 0.006″, or any other desired radius of curvature.
Similarly, the second forming member 30a includes a first forming portion 32a that has a first engaging surface 33a at a distal end thereof, a second forming portion 34a that has a second engaging surface 35a at a distal end thereof, a third forming portion 36a that has a third engaging surface 37a at a distal end thereof, and a fourth forming portion 38a that has a fourth engaging surface 39a at a distal end thereof. The engaging surfaces 33a, 35a, 37a, 39a are configured to engage the formable material 12 on one side thereof and deform the formable material 12 into a desired shape, as discussed in further detail below. Each of the forming portions 32a, 34a, 36a, 38a may generally be elongated or finger-like in shape, as illustrated, but the illustrated embodiments should not be considered to be limiting in any way. For example, in an embodiment, the second forming member 30a may be a single piece of material that is shaped to provide the engaging surfaces 33a, 35a, 37a, 39a on one side thereof. Similar to the engaging surfaces 33, 35, 37, 39 illustrated in
As illustrated in
The first forming member 20 and the second forming member 30 may be moved relative to the feeder 14 in an X-Y plane by actuators 40, 50, respectively, that are schematically illustrated in
In operation, the first forming member 20 is initially positioned on one side of the axis AX, and the second forming member 30 is initially positioned on the opposite side of the axis AX relative to the first forming member 20 such that one of the engaging surfaces 23, 25, 27, 29 of the first forming member 20 and one of the engaging surfaces 33, 35, 37, 39 of the second forming member 30 face each other. Although
In an embodiment, the controller 16 sends a signal to the feeder 14 to advance the formable material 12 by a predetermined amount or length in the first direction FD substantially along the axis AX. In an embodiment, the feeder 14 does not actively advance the formable material 12, but instead allows the formable material 12 to be drawn by the first forming member 20 and/or the second forming member 30, as understood by one of ordinary skill in the art.
As illustrated in
As illustrated in
The first forming member 20 then moves in the second direction SD towards the formable material 12, engages the formable material 12 with the third engaging surface 27, as illustrated in
Similar to the movement of the first forming member 20 that is represented in
The second forming member 30 then moves in the third direction TD towards the formable material 12, as illustrated in
Similar to the movement of the first forming member 20 illustrated in
The first forming member 20 then moves in the second direction SD towards the formable material 12, as illustrated in
Similar to the movement of the second forming member 30 that is represented in
The second forming member 30 then moves in the third direction TD towards the formable material 12, as illustrated in
Similar to the movement of the first forming member 20 illustrated in
The first forming member 20 then moves in the second direction SD towards the formable material 12, as illustrated in
Similar to the movement of the second forming member 30 that is represented in
The second forming member 30 then moves in the third direction TD towards the formable material 12, as illustrated in
As illustrated in
After the portion of the wave form has been formed, as illustrated in
The first forming member 20 and the second forming member 30 may be moved away from the wave form being created at any time and moved as illustrated in, for example,
It has been found that the method of creating the wave form that is illustrated in
The steps illustrated in the embodiment of
After the apparatus has completed the methods illustrated by
Although the wave form 100 illustrated in
The controller 16 may be programmed with the desired wave form and corresponding signals may be communicated to the feeder 14 and the actuators 40, 50 that move the first and second forming members 20, 30, so that the first and second forming members 20, 30 are moved relative to the feeder 14 and the formable member 12 accordingly. The forming apparatus 10 uses multi-axis motions to deform the formable material 12 and create a specific wave form or stent pattern that creates a stent having substantially perpendicular ends when wound about mandrel or other suitable structure. In an embodiment, the forming apparatus uses a multi-slide to create the multi-axis motions, but it is not necessary to use a multi-slide to create such motions. Other arrangements are contemplated to be within the scope of the invention. In addition, the controller 16 may send corresponding signals to the motors or actuators that provide movement to the first and second forming members 20, 30 to change the radii of the crowns and/or the length of the substantially straight segments.
The formable material 12 may be a wire or strip material that plastically deforms when deformed by the first and second forming members 20, 30 so that the wave form generally holds its shape after being formed. By adjusting the shape and size of the first and second forming members 20, 30, the relative motions of the first and second forming members 20, 30 in relation to each other, the formable material 12, and the feed rate or draw rate and/or movement of the feeder 14, various amplitudes, periods, and shapes may be created within the wave form to form the overall desired shape for the stent.
Embodiments of the stents made using the method and apparatus discussed above may be formed from a wire or a strip of suitable material. In certain embodiments, the stents may be formed, i.e., etched or cut, from a thin tube of suitable material, or from a thin plate of suitable material and rolled into a tube. Suitable materials for the stent include but are not limited to stainless steel, iridium, platinum, gold, tungsten, tantalum, palladium, silver, niobium, zirconium, aluminum, copper, indium, ruthenium, molybdenum, niobium, tin, cobalt, nickel, zinc, iron, gallium, manganese, chromium, titanium, aluminum, vanadium, carbon, and magnesium, as well as combinations, alloys, and/or laminations thereof. For example, the stent may be formed from a cobalt alloy, such as L605 or MP35N®, Nitinol (nickel-titanium shape memory alloy), ABI (palladium-silver alloy), Elgiloy® (cobalt-chromium-nickel alloy), etc. It is also contemplated that the stent may be formed from two or more materials that are laminated together, such as tantalum that is laminated with MP35N® alloy. The stents may also be formed from wires having concentric layers of different metals, alloys, or other materials. Embodiments of the stent may also be formed from hollow tubes, or tubes that have been filled with other materials. The aforementioned materials and laminations are intended to be examples and are not intended to be limiting in any way.
While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient roadmap for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of members described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.
Claims
1. A method for forming a wave form for a stent, the method comprising:
- providing a length of a formable material from a supply of the formable material in a feeder along an axis in a first direction in between a first forming member and a second forming member, the second forming member being positioned closer to the feeder than the first forming member;
- moving a first forming portion of the first forming member across the axis in a second direction substantially perpendicular to the first direction to engage and deform the formable material while engaging the formable material with a first forming portion of the second forming member;
- moving the first forming portion of the first forming member and the first forming portion of the second forming member across the axis in a third direction that is substantially opposite the second direction to draw and form the formable material over the first forming portion of the second forming member;
- disengaging the first forming member from the formable material;
- moving the first forming member in a fourth direction such that a second forming portion of the first forming member is substantially aligned with the formable material, wherein the fourth direction is substantially perpendicular to the first direction, the second direction, and the third direction;
- moving the first forming member and the second forming member relative to each other so that the first forming member is positioned closer to the feeder than the second forming member;
- moving the second forming portion of the first forming member into engagement with the formable material; and
- moving the second forming portion of the first forming member and the first forming portion of the second forming member across the axis in the second direction to draw and form the formable material over the second forming portion of the first forming member.
2. The method according to claim 1, wherein the first forming portion of the first forming member has a distal end having a first radius and the second forming portion of the first forming member has a distal end having a second radius that is different from the first radius.
3. The method according to claim 1, further comprising:
- disengaging the second forming member from the forming material;
- moving the second forming member the fourth direction substantially perpendicular to the first direction, the second direction, and the third direction;
- moving the first forming member and the second forming member relative to each other so that the second forming member is positioned closer to the feeder than the first forming member;
- moving a second forming portion of the second forming member into engagement with the formable material; and
- moving the second forming portion of the first forming member and the second engaging portion of the second forming member across the axis in the third direction to draw and form the formable material over the second forming portion of the second forming member.
4. The method according to claim 3, wherein the first forming portion of the second forming member has a distal end having a first radius and the second forming portion of the second forming member has a distal end having a second radius that is different from the first radius.
5. The method according to claim 1, wherein the providing comprises drawing a length of the formable material with the first forming member and/or the second forming member.
6. The method according to claim 1, wherein the providing comprises feeding a length of the formable material with a feeder.
7. The method according to claim 1, wherein the formable material is a wire.
8. The method according to claim 1, wherein the formable material is a strip of material.
9. A method for forming a wave form for a stent, the method comprising:
- providing a length of a formable material from a supply of the formable material in a feeder along a feed axis in a first direction in between a first forming member and a second forming member, the second forming member being positioned closer to the feeder than the first forming member;
- moving a first forming portion of the first forming member into contact with the formable material and across the feed axis in a second direction substantially perpendicular to the first direction; and
- folding the formable material over a first forming portion of the second forming member by moving the second forming member and the first forming member in a third direction substantially opposite the second direction and moving the second forming member and the first forming member in a fourth direction substantially opposite the first direction;
- disengaging the first forming member from the formable material;
- moving the first forming member in a fifth direction, such that a second forming portion of the first forming member is substantially aligned with the formable material, wherein the fifth direction is substantially perpendicular to the first direction, the second direction, the third direction, and the fourth direction;
- moving the second forming portion of the first forming member into engagement with the formable material at a position closer to the feeder than the second forming member;
- drawing a length of the formable member from the feeder with the first forming member and the second forming member; and
- folding the formable material over the second forming portion of the first member by moving the first forming member and the second forming member in the second direction and moving the first forming member and the second forming member in the fourth direction.
10. The method according to claim 9, wherein the first forming portion of the first forming member has a first radius and the second forming portion of the first forming member has a second radius different from the first radius.
11. The method according to claim 9, further comprising:
- disengaging the second forming member from the forming material;
- moving the second forming member in the fifth direction substantially perpendicular to the first direction, the second direction, and the third direction;
- moving a second forming portion of the second forming member into engagement with the formable material at a position closer to the feeder than the first forming member;
- drawing a length of the formable member from the feeder with the first forming member and the second forming member; and
- folding the formable material over the second forming portion of the second forming member by moving the second forming member and the first forming member in the third direction and moving the second forming member and the first forming member in the fourth direction.
12. The method according to claim 11, wherein the second forming member and the first forming member are moved in the third direction and then are moved in the fourth direction sequentially.
13. The method according to claim 11, wherein the second forming member and the first forming member are moved in the third direction and in the fourth direction simultaneously.
14. A stent defined by a wave form prepared by a process comprising the steps of:
- providing a length of a formable material from a supply of the formable material in a feeder along an axis in a first direction in between a first forming member and a second forming member, the second forming member being positioned closer to the feeder than the first forming member;
- moving a first forming portion of the first forming member across the axis in a second direction substantially perpendicular to the first direction to engage and deform the formable material while engaging the formable material with a first forming portion of the second forming member;
- moving the first forming portion of the first forming member and the first forming portion of the second forming member across the axis in a third direction that is substantially opposite the second direction to draw and form the formable material over the first forming portion of the second forming member;
- disengaging the first forming member from the formable material;
- moving the first forming member in a fourth direction such that a second forming portion of the first forming member is substantially aligned with the formable material, wherein the fourth direction is substantially perpendicular to the first direction, the second direction, and the third direction;
- moving the first forming member and the second forming member relative to each other so that the first forming member is positioned closer to the feeder than the second forming member;
- moving the second forming portion of the first forming member into engagement with the formable material; and
- moving the second forming portion of the first forming member and the first forming portion of the second forming member across the axis in the second direction to draw and form the formable material over the second forming portion of the first forming member.
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Type: Grant
Filed: Apr 18, 2012
Date of Patent: Jan 19, 2016
Patent Publication Number: 20130277884
Assignee: Medtronic Vascular, Inc. (Santa Rosa, CA)
Inventors: Erik Griswold (Penngrove, CA), Lance Ensign (Santa Rosa, CA)
Primary Examiner: Edward Tolan
Application Number: 13/450,309
International Classification: B21D 11/07 (20060101); B21D 13/02 (20060101);